const sum = (num1, num2) => num1 + num2;

//1.只导出一个
module.exports = sum;

//2.导出多个(写法一)
const PI = 3.14;
class SomeMathObject{
    constructor(){
        console.log('SomeMathObject Constructor Console');
    }
}

module.exports.sum = sum;
module.exports.PI = PI;
module.exports.SomeMathObject = SomeMathObject;

//3.导出多个(写法二)
module.exports = {sum:sum,PI:PI,SomeMathObject:SomeMathObject};
